JPH0769423B2 - Rangefinder and approach speedometer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an approach speedometer used as a berth speedometer for a berth assist system of a large ship.

(Prior Art) When a large vessel such as a tanker for ocean voyage is docked at a jetty, if the docking speed is too high, the jetty of a relatively delicate structure may be destroyed.

For this reason, as shown in FIG. 11, the ship 100 is held parallel to the pier 200 several hundred meters offshore, and two tugboats 101 and 102 are jointly operated at two points on the bow side near the bow and near the stern. By controlling the jetty at a constant speed, the pier is controlled so as to slowly berth while maintaining the parallel state with the jetty. At this time, the berthing speed of the ship is measured one by one on the pier side, and feedback control is notified to the doug boat side. In addition, in this specification, the approaching motion of the ship toward the pier or the quay is referred to as “berthing”.

Conventionally, an ultrasonic radar has been used as the above-mentioned berthing speed meter. That is, as shown in FIG. 11, ultrasonic radars 201 and 202 are installed in the seawater on the quay side. Each ultrasonic radar consists of a pair of ultrasonic radiator and receiver.The ultrasonic wave emitted from the radiator propagates in the sea and is reflected by the side of the ship below the waterline, and propagates in the sea again to propagate the ultrasonic radar. It returns to and is received by the receiver. The distance between the quay and the ship is measured from this round-trip travel time and a constant propagation speed, and the berthing speed is measured from the time change rate of this measured distance. This berthing speed is measured independently for at least two locations on the ship, as shown in FIG. 11, for the purpose of maintaining the parallel state with the quay.

For further details of such a berth speed meter using ultrasonic waves, refer to the specification of JP-A-52-86353, which is entitled "Vessel berth guidance device," as necessary.

(Problems to be Solved by the Invention) The above-mentioned conventional berthing speed meter utilizing ultrasonic waves utilizes the property that ultrasonic waves travel straight at a constant propagation speed in the sea. However, with this method, it is affected by various obstacles such as fish in the sea, debris, bubbles, and ultrasonic waves emitted may pass through the bottom of the hull depending on weather conditions such as waves and tide levels. There is a problem in terms of reliability.

Setting the propagation path of this ultrasonic wave in the air rather than in the sea is difficult in that the amount of attenuation during propagation becomes excessive and the propagation path is curved due to the influence of wind.

Further, in this ultrasonic radar, since the wavelength of the ultrasonic waves is sufficiently larger than the unevenness of the surface of the ship that reflects the ultrasonic waves, the ultrasonic waves that collide with the ship will undergo regular reflection such that the incident angle and the reflection angle are equal. receive. For this reason, as illustrated in Fig. 12, as the parallel relationship between the ship and the pier collapses during berthing, the ultrasonic waves reflected on the side of the ship are received by the receiver installed in pairs with the radiator. There is also a problem that it disappears and measurement becomes impossible.

On the other hand, referring to the specification of Japanese Patent Application Laid-Open No. 54-51793, which is entitled "Navigation Assistance Device", a method of using a radio wave detector whose propagation path is in seawater or air can be considered. However, according to the inventor's idea, this radio wave detector has the following drawbacks.

First, there is a problem that a large facility such as an antenna is required, which increases the establishment cost, and a large amount of electric power is required, which also increases the operation cost.

Further, in this radio wave detector, similarly to the case of the ultrasonic radar, since the emitted radio wave is regularly reflected on the side of the ship, there is a problem that measurement becomes impossible if the parallelism between the ship and the quay collapses to some extent.

Further, this radio wave detector has a problem that it is difficult to independently measure the berthing speed at a plurality of locations of the ship because the radio wave has a large wavelength and the resolution is not sufficient.

Further, the radio wave detector also causes a problem of electromagnetic compatibility of peripheral systems, such as inducing interference in a nearby communication facility.

(Means for Solving the Problem) A rangefinder according to the present invention includes first and second oscillating units for oscillating a drive pulse and a sampling pulse having slightly different periods (frequency), and the drive pulse for an object. A laser diode for emitting a laser beam pulse in synchronism with the laser diode, and a light emitting unit including a light transmitting lens for converging the laser beam emitted from the laser diode; and a light receiving lens for converging a laser beam pulse reflected by an object, A light receiving section including an avalanche photodiode for converting the converged laser beam pulse into an electric signal and outputting the electric signal, and holding the electric signal output from the light receiving section a plurality of times in synchronization with the sampling pulse. The electric signal corresponding to the time axis of the received laser beam pulse is extended by And a distance calculation for calculating the distance to the object by detecting the time difference from the emission point to the reception point of the laser beam pulse based on the electric signal output from the sample and hold section. And a section.

Furthermore, the distance meter of the present invention is configured to equalize the phase difference between the beat signal of the drive pulse and the sampling pulse output from each of the first and second vibrating units and the frequency-divided signal of one pulse. It has a phase-locked loop that controls the oscillation frequency of one of the oscillators.

Further, according to the rangefinder of the present invention, the size of the field of view of the light receiving lens is set to a value equal to or slightly different from the size of the irradiation spot formed on the object by the laser beam pulse emitted from the light emitting section. At the same time, the light-transmitting lens of the light-emitting unit and the light-receiving lens of the light-receiving unit are arranged so that their optical axes are parallel to each other, along the respective optical axis directions, and the distances between the optical axes are equal to each other. It is installed with a value equal to or slightly different from the half value of the sum.

(Operation) It is assumed that the sampling timing for the received pulse signal is sequentially shifted by Δτ due to a slight difference in frequency (frequency) between the drive pulse and the sampling pulse. If the width of the received pulse is W (sec), the number of times that a non-zero sample value is obtained for this received pulse is W / δτ times. Then, since each non-zero sampling value is held for the sampling period τ (sec), the received pulse is extended to τ (sec) per sampling number. As a result, the width of the received pulse after sample hold is τ (sec / time) × W /
δτ (times) = (τ / δτ) W (sec). Therefore,
The width of the pulse signal output from the sample and hold unit is [(τ / δτ) W] / W = τ / δτ = (τ ₀ + δτ) / δτ ≈τ ₀ / δτ (1) It will be doubled. In this way, by extending the width of the received pulse signal on the time axis, the reception time point of the received pulse can be detected with high accuracy.

Hereinafter, the present invention will be described in more detail with reference to Examples.

(Embodiment) FIG. 1 is a block diagram showing the configuration of a berth speedometer according to an embodiment of the approach speedometer of the present invention.

In the figure, 10 is a main oscillator, 11 is a frequency divider, 12 and 15 are amplifiers, 13 is a light emitting section, 14 is a light receiving section, 16 and 18 are sample and hold circuits, 17 is a binarization circuit, and 20 is a sub oscillator. , 21 and 23 are frequency dividers, 22 is a mixer, 24 is a phase comparator, 25 is a reduction pass filter, 30 is a CPU, 31 and memory, and 32 is a memory controller.

The main oscillator 10 is mainly composed of a stable crystal oscillator, and generates a pulse train having an oscillation frequency Fo. This pulse train is decimated to 1 / N in the frequency divider 11, becomes a drive pulse having a constant repetition frequency fo (= Fo / N), and is supplied to the light emitting unit 13 via the amplifier 12. The light emitting unit 13 includes a laser diode (LD) and an LD drive circuit for driving the laser diode, drives the laser diode in synchronization with the drive pulse train supplied from the amplifier 12, and has a cycle τo (= 1/1 /
fo) emits a pulsed laser beam. The light emitting unit 13 is installed at a predetermined position on the sea surface such as a quay wall, and emits a pulsed laser beam in front of the quay and in a direction orthogonal to the quay.

Typical characteristic values of the laser beam emitted from the light emitting unit 13 are: half width; 3 ns, output; 200 W (PEP: peak envelope power), wavelength: 850 nm, repetition period: 5 μs
Is.

The pulsed laser beam emitted from the light emitting unit 13 is propelled by the doug boat, reflected by the bow of the ship on the shore or near the stern, and enters the light receiving unit 14. Light receiving section
14 is mainly composed of an avalanche photodiode (APD), and outputs an electric signal having an amplitude according to the amount of received light. Therefore, each time the reflected component of the pulsed laser beam is received, a pulsed electric signal is output from the light receiving unit 14. The pulsed electric signal is amplified in the amplifier 15 while being subjected to amplitude limitation so that the peak value becomes a predetermined value, and then is supplied to the sample and hold circuit 16. This sample and hold circuit 16 includes a sub oscillator 20
The pulse train generated in 1 is frequency-divided by the frequency divider 21 and is supplied as a sampling pulse having a period τ. The pulse-shaped electric signal output from the amplifier 15 is synchronized with the sampling pulse, and the sample-and-hold circuit 16
Is stored in the binarization circuit 17 and is output to the binarization circuit 17.

The output of the sample and hold circuit 16 is binarized by being compared with a predetermined threshold value in the binarization circuit. That is, if the output of the sample and hold 16 does not reach the above threshold value, the binary signal "0" is output from the binarization circuit 17,
2 if the output of sample and hold 16 is above the threshold
The binarization circuit 17 outputs a binary signal "1". The output of the binarization circuit 17 is written in the memory 31 under the control of the memory controller 32. The pulse output from the amplifier 12 is sampled and held in the sample and hold circuit 18 in synchronization with the frequency-divided pulse of the sub oscillator 20, and is supplied to the memory controller 32. Each time the memory controller 32 receives a pulse output from the sample and hold circuit 18, the memory controller 32 advances the address counter and writes the output of the binarization circuit 17 into the memory 31. Therefore,
The CPU 30 detects the address at which the write data changes from continuous “0” to continuous “1” by accessing the memory 31 while advancing the address, and the radiation pulse is detected from this address value. The time difference between the received pulses i.e.
The propagation delay time can be detected.

The CPU 30 calculates the distance to the ship under berth from the propagation delay time and the speed of light, and calculates the berthing speed of the ship from the time change speed (rate of change) of this distance. The CPU 30 displays the calculated berthing speed on a display device (not shown), or automatically sends the calculated berthing speed to a tugboat or the like under berthing work from a transmitter (not shown).

The two berth speedometers of FIG. 1 are typically installed on the quay 200 at a predetermined distance, as illustrated by reference numerals 1 and 2 in FIG. The light emitting portions of the berth speedometers 1 and 2 emit laser beams to the boat side near the bow and the boat side near the stern of the ship 100, which is propelled by the tugs 101 and 102 and berths substantially parallel to the quay 200. Since the surface of the ship that reflects the emitted laser beam has a rough surface having irregularities sufficiently larger than the wavelength of the laser beam, the incident laser beam is isotropically scattered by this rough surface. That is, as shown in FIG. 2, when the incident surface of the laser beam is represented by an incident point, a reflected beam having a spherical directivity is emitted from this incident point.

Therefore, as illustrated in FIG. 3, even if the parallelism between the ship 100 and the quay 200 while docking is broken, the directivity of the reflected laser beam is so wide that the light receiving sensitivity of the light receiving section is insufficient, and detection becomes impossible. There is no such thing. Due to this wide directivity, the berth speed meter 1
The reflected waves of the laser beam emitted from each of No. 2 and No. 2 also reach the light receiving unit of the other party. However, it is possible to easily avoid mutual interference due to reception of reflected waves of the other party by giving the light receiving section of each berth speed meter an appropriate directivity.

By the way, the berth speed meter of FIG. 1 uses a laser beam having a propagation speed that is orders of magnitude higher than that of ultrasonic waves. For this reason, the propagation delay time of the reflected wave becomes orders of magnitude shorter than that of the ultrasonic wave, and it becomes difficult to measure the propagation delay time with high accuracy by an ordinary method. In addition, this berth speed meter uses a laser beam with a wavelength that is orders of magnitude shorter than radio waves. For this reason, a radar that uses radio waves cannot adopt a method of measuring the propagation delay time of a reflected wave from the amplitude difference and phase difference of the effective transmitted and received modulated waves.

Therefore, in the berthing speed meter shown in FIG. 1, the required measurement accuracy is secured by using the following sampling method.

That is, referring to the waveform diagram of FIG. 4, the laser beam pulse is repeatedly emitted with a constant period τo, as shown in FIG. As a result, as illustrated in FIG. 6B, the reflected laser beam pulse is received with a delay of propagation delay time τd from the emission time point of each laser beam pulse. However, if the berthing speed of the ship is v and the distance to the ship is r, increase the repetition frequency fo (= 1 / τo) of the laser beam pulse by an order of magnitude greater than the expected value of v / r. The propagation delay time τd detected by
Are set to be equal. In order to detect this delay time τd with high accuracy, it is necessary to detect the received pulse waveform with high accuracy. Therefore, as illustrated in FIG. 4 (C), sampling / sampling with a period τ slightly larger than τo is performed.
The pulse is supplied from the frequency divider 21, and the received pulse output from the amplifier 15 is held in the sample and hold circuit 16 in synchronization with this sampling pulse.

Assuming that the difference between the sampling pulse period τ and the laser beam pulse period τo is δτ, it is clear from the comparison between (A) and (C) in FIG. 4 that the first sampling pulse is the laser beam.・ Although it occurs at the same time as the pulse, from the next time onward, it will be delayed by δτ from the laser beam pulse. Therefore, paying attention to the relative relationship on the time axis between this sampling pulse and the reception pulse illustrated in (B), the latter is sampled and held by the former at a time interval of δτ. Since the sampling and holding are performed in the period of τ, the time axis of the received pulse waveform output from the sample and hold circuit 16 is as described above by the equation (1), as will be understood by referring to (D). Will be expanded by the magnification given by.

In the example shown in FIG. 4 (D), δτ is too large compared to the width of the original reflected pulse, so that the waveform whose time axis is enlarged is a rough waveform. In practice, a sufficiently smooth time-axis expanded waveform can be obtained by setting δτ to a value sufficiently smaller than the width of the original reflected pulse.

The value τo / δτ of the equation (1) is also the total number of laser beam pulses emitted for one distance measurement. If the total number of radiation required for this one-time distance measurement is Σn, Σn ≈ τo / δτ (2) In order to realize time extension by such a sampling method, the main oscillator 10 and sub oscillator The 20 oscillation frequencies are determined based on the following considerations.

That is, first, the measurable range (the longest measurable distance) of this berth speed meter is R meters (m), and the speed of light is C
(M / s), the propagation delay time τmax (s) of the laser beam pulse reflected and received from the ship located at the farthest distance R is τmax = 2R / C (s) (3) ).

Therefore, in order to secure the measurable range of R (m),
It is necessary to set the period τo of the light emission pulse for driving the light emitting unit 13 to be τmax or more in the equation (1). Here, τo = τmax = 2R / C (s) (4) is set.

The repetition frequency fo of the light emission pulse is fo = 1 / τo = C / 2R (1 / s) (5).

If the frequency division ratio of the frequency divider 11 is set to N, the oscillation frequency Fo of the main oscillator 10 becomes Fo = Nfo = NC / 2R (1 / s) (6).

On the other hand, if the distance measurement resolution is set to δR (m), the propagation delay time measurement resolution δτ based on this is δτ = 2δR / C (s) (7).

Therefore, the period τ of the sampling pulse output from the frequency divider 21 may be set to τ = τo + δτ = (2R + 2δR) / C (s) (8). Further, the repetition frequency f of the sampling pulse is f = 1 / τ = C / (2R + 2δR) (1 / s) (9).

Here, if the frequency division ratio of the frequency divider 21 is set to the same value N as the frequency division ratio of the frequency divider 11, the oscillation frequency F of the sub-oscillator 20 is F = Nf = NC / (2R + 2δR) (1 / s)… (10)

From equations (6) and (10), δF = Fo−F = NCδR / [2R (R + δR)] ≈NCδR / (2R ² ) ... (11) Equations (6), (11) and (7) From the formula and the formula (8), δF / F _o ≈ [NCδR / (2R ² )] / [NC / (2R)] = δR / R = [Cδτ / 2] / [C (τ-δτ) / 2 ] = Δτ / (τ-δτ) = δτ / τ _o (12) Here, the measurable range R is 750 m and the measurement resolution δR is 1 cm.
If it is (0.01m), δF / Fo = 1.333 × 10 ^-5 (13) is obtained from the equation (10).

It is extremely difficult to hold such a minute difference in oscillation frequency in the main oscillator 10 and the sub oscillator 20 that operate independently of each other. Therefore, as shown in FIG.
By configuring the sub-oscillator 20 with a voltage controlled oscillator (VCO) and configuring a phase-locked loop including a mixer 22, a frequency divider 23, a phase comparator 24, and a low-pass filter 25,
The oscillation frequency F of the sub oscillator 20 is made to follow the value lower than the oscillation frequency Fo of the main oscillator 10 by δF. This δF is δF = Fo / MN (14), where M is the frequency division ratio of the frequency divider 23.

Hereinafter, a specific method of setting a numerical value based on the above consideration will be described.

First, 750 m is set as the measurable range R. From this measurable range R and the equation (4), 5.00 μs (microsecond) is obtained as the radiation period τo of the laser beam. This is 200k
It corresponds to the repetition frequency fo of Hz. Next, the distance measurement value is obtained at a rate of 5 times per second. Accordingly, the time required for one measurement is 200 ms (millisecond). Therefore, 1
Total number of laser pulse beams emitted for each measurement Σ
n is Σn = 200 kHz × 200 ms = 4 × 10 ⁴ . This Σn is equal to τo / δτ from equation (2), which is also equal to R / δR from equation (12).

Therefore, the measurement resolution δR is 750 m / (4 × 10 ⁴ ) = 1.87
Get 5 cm. Further, if the frequency division ratio N is 750, from the formula (6), the oscillation frequency Fo of the main oscillator 10 is 750 × 200 kH
Get z = 150MHz. From equation (12), δF = 150MHz /
(4 × 10 ⁴ ) = 3.75 KHz is obtained.

FIG. 5 shows an example of four numerical values set by trial and error in this way.

6 and 7 are a perspective view and a side view showing the physical configuration of the berthing speed meter of FIG.

In each of the above figures, 41 is a light emitting part lens holding barrel, 42 is a light emitting part slide barrel, 43 is an arrangement adjusting mechanism, 44 is a laser diode heat sink, 45 is a laser diode unit case, 51a and 51b are light receiving part lenses A holding barrel, 52 is a light-receiving slide barrel, 53 is an APD mount, 54 is an APD unit case, 61 is a printed wiring board, and 62 and 63 are mount panels.

On the printed wiring board 61, the light emitting portion 13 of the circuit shown in FIG.
The circuit of FIG. 1 excluding the light receiving portion 14 is assembled. The physical assembly shown in FIG. 6 is housed in an explosion-proof housing having a predetermined shape after adding a frame and a chassis.

The light emitting surface of the laser diode housed in the laser diode unit case 45 is about 0.5 mmφ, and the laser beam is emitted from here at a divergence angle of 20 ° to 30 °. Therefore, this laser diode can be considered as a simple filament except that the amount of emitted light is extremely large. On the other hand, the light receiving area of the APD is about 1.0 mmφ which is almost twice as large as the light emitting surface of the laser diode.
Therefore, by setting the focal length of the light receiving lens to be approximately twice as large as the focal length of the light emitting lens, only the irradiation beam formed on the side of the vessel is automatically selected as the visual field of the light receiving unit. It will be possible. As a result, light reception is realized under the highest S / N ratio. According to this embodiment, an achromatic lens having a focal length of 120 mm and a diameter of 400 mm is used as the light emitting lens, and an achromatic lens having a focal length of 240 mm and a diameter of 63 mm is used as the light receiving lens.

Further, as shown in FIG. 8, in order to use each of the light-emitting lens 40 and the light-receiving lens 50 to the limit of the effective diameter while keeping the mutual distance to a minimum, each of them is moved back and forth along the optical axis. Are arranged. By arranging the lenses in such a manner that they are offset from each other in the optical axis direction, as shown in the front view of FIG. 9, the distance between the lenses is minimized in spite of the thickness of each lens barrel. Each can be used up to the effective diameter limit while maintaining.

In order for the light receiving part to keep only the spot formed on the side of the vessel of the ship under berth by the laser beam emitted from the light emitting part in the field of view, in addition to selecting the focal length of each of the above parts, Need to cross at. Therefore,
An optical axis adjustment mechanism between the lens barrels of each part is required. According to the present embodiment, the optical axis adjusting mechanism between the lens barrels is replaced with a simple arrangement adjusting mechanism to realize the cost reduction. That is, the optical axis of the lens barrel of each part is fixed in parallel, by adjusting the arrangement of the laser diode by the arrangement adjusting mechanism 43 with respect to the optical axis of the light emitting lens barrel 41, 42,
The equivalent optical axis adjustment is realized.

FIG. 10 is an exploded perspective view showing the configuration of the arrangement adjusting mechanism 43.

This arrangement adjusting mechanism includes a plate 72 fixed to the slide barrel 42.
A plate 73 superposed on the plate 72 so as to be displaceable in the X-axis direction, a plate 74 superposed on the plates 72 and 73 so as to be displaceable in the Y-axis direction, and a displacement between these plates. It is composed of a group of accessories such as openings, pins, screw holes, screws, springs, etc.

First, the plate 72 is attached to the slide barrel by screwing (not shown).
Fixed at 42. Next, the plate 73 is superposed on the plate 72 so as to be displaceable in the X-axis direction. That is, the pin 80 in the pin holes 78 and 79.
Is inserted and the pin 77 is inserted into the pin hole 75 and the long hole 76, the plates 72 and 73 are overlapped while leaving the freedom of rotation around the pin 80. Next, the spring 83 and the opening
A screw 84 is screwed into the screw hole 81 through 82. This screw 84
By adjusting the screwing depth of the plate 73, the plate 73 rotates about the pin 80 with respect to the plate 72, and accordingly, a displacement component in the X-axis direction is generated.

Similarly, the plate 74 is superposed on the plates 72 and 73 so as to be displaceable in the Y-axis direction. That is, pin 87 in pin holes 85 and 86
Is inserted and the pin 90 is inserted into the pin hole 88 and the long hole 89, the plates 73 and 74 are superposed while leaving the freedom of rotation around the pin 87. Next, the spring 93 and the opening
The screw 94 is screwed into the screw hole 91 through the screw hole 92. This screw 94
By adjusting the screwing depth of the plate 74, the plate 74 rotates about the pin 87 with respect to the plate 73, and accordingly, a displacement component in the Y-axis direction is generated.

The berth speedometer for ships has been described above.
However, it is obvious that the present invention can be extended as an approach speedometer for moving bodies other than ships.

In addition, the distance to a moving body such as a ship is measured in a predetermined cycle,
The case of measuring the approach speed from the reduction rate has been described.
However, it is clear that this can be extended to a rangefinder that simply measures the distance to a stationary or moving object.

(Effect of the Invention) As described in detail above, the approach speedometer of the present invention calculates the distance to a moving body such as a ship by detecting the time from the emission point of a laser beam pulse to the reception point. It has a configuration that calculates the approaching speed of a moving object from the calculated time change rate of distance, so unlike conventional radars that use ultrasonic waves or radio waves, it is possible to realize economical measurement with high reliability. The effect is played.

Further, the approach speedometer of the present invention realizes the stability of a minute frequency difference between the drive pulse and the sampling pulse by adding a special phase clock loop, and at the same time, establishes the visual field of the light receiving lens and the positional relationship with the light transmitting lens. Since it is configured to realize a high S / N ratio by optimizing, it is possible to realize high detection accuracy together with the extension of the time axis of the received pulse signal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of a berth speedometer according to an embodiment of the approaching speedometer of the present invention, and FIGS. 2 and 3 are the use of the berth speedometer of the above embodiment. A plan view to explain the situation,
FIG. 4 is a waveform diagram for explaining the operation of the berth speedometer of the above embodiment, FIG. 5 is a conceptual diagram showing an example of setting items relating to the operation of the berth speedometer of the above embodiment, FIGS. 6 and 7. The figure is first
FIG. 8 is a perspective view and a side view showing the physical configuration of the berthing speed meter in the figure, and FIGS. 8 and 9 are sectional views, front views, and 10 for explaining the spatial arrangement of the light-emitting lens and the light-receiving lens. Is an exploded perspective view for explaining the configuration of the arrangement adjusting mechanism that substitutes the optical axis adjustment of the light emitting part and the light receiving part, and FIGS. 11 and 12 show the usage situation and problems of the conventional berth speed meter with ultrasonic radar. It is a top view for explaining. 1,2 shore speedometer, 10 ...... main oscillator, 11,21 ...... divider, 12,15 …… amplifier, 13 …… light emitting part, 14 …… light receiving part, 16,18 …… sample ・Hold circuit, 17 …… Binarization circuit, 20 …… Sub oscillator, 30 …… CPU, 31 …… Memory, 3
2 ... Memory controller, 41 ... Lens holding lens barrel for light emitting unit, 42 ... Slide barrel for light emitting unit, 43 ... Arrangement adjusting mechanism,
44 …… Laser diode heat sink, 45 …… Laser diode unit case, 51a, 51b …… Light receiving part lens holding lens barrel, 52 …… Light receiving part slide lens barrel, 53 …… APD mount, 54 …… APD unit Case, 61 …… Printed wiring board, 62,63 …… Mount panel, 100 …… Vessel on berth, 101,102 …… Tugboat, 200 …… Wharf.

Claims (4)

[Claims] 1. A first oscillator for generating a drive pulse repeated in a first cycle, and a second oscillator for generating a sampling pulse repeated in a second cycle slightly larger than the first cycle. Of the drive pulse output from the first oscillating section and the sampling pulse output from the second oscillating section, and the phase difference between the divided signal of one of the pulses. A phase-locked loop that controls the oscillation frequency of the first or second oscillator, a laser diode that emits a laser beam pulse to an object in synchronization with the drive pulse, and a laser beam emitted from the laser diode. A light-emitting portion including a light-transmitting lens that converges the laser beam, a light-receiving lens that converges the laser beam pulse reflected by the object, and the converged laser beam pattern. A light receiving portion including an avalanche photodiode for converting a pulse into an electric signal and outputting the electric signal; and holding the electric signal output from the light receiving portion a plurality of times in synchronization with the sampling pulse, thereby receiving the received laser light. A sample-and-hold section that outputs an electric signal corresponding to an expanded time axis of the beam pulse, and an electric signal output from the sample-and-hold section, from the time when the laser beam pulse is emitted until the time when the laser beam pulse is received. And a distance calculation unit that calculates a distance to the object by detecting a time difference, and the size of the field of view of the light-receiving lens is the irradiation spot created by the laser beam pulse emitted from the light-emitting unit on the object. The light-transmitting lens of the light-emitting unit and the light-receiving lens of the light-receiving unit are ,
Installed in parallel to each optical axis, in front of and behind each optical axis direction, and with the distance between the optical axes kept equal to or slightly different from half the sum of the diameters. Distance meter characterized by. 2. A first oscillating section for generating a drive pulse repeated in a first cycle, and a second oscillating section for generating a sampling pulse repeated in a second cycle slightly larger than the first cycle. Of the drive pulse output from the first oscillating section and the sampling pulse output from the second oscillating section, and one of the pulse-divided signals have the same phase difference. A phase-locked loop that controls the oscillation frequency of the first or second oscillator, a laser diode that emits a laser beam pulse to an object in synchronization with the drive pulse, and a laser beam emitted from the laser diode. A light emitting unit including a converging light transmitting lens, a light receiving lens for converging a laser beam pulse reflected by the object, and the converged laser beam pulse A light receiving unit including an avalanche photodiode for converting the optical signal into an electric signal and outputting the electric signal, and holding the electric signal output from the light receiving unit a plurality of times in synchronization with the sampling pulse, thereby receiving the received laser beam. A sample-and-hold section that outputs an electric signal corresponding to an expanded time axis of the beam pulse, and an electric signal output from the sample-and-hold section, from the time when the laser beam pulse is emitted until the time when the laser beam pulse is received. A distance calculation unit that calculates a distance to the object by detecting a time difference, and an approach speed calculation unit that calculates an approach speed of the object from the time change rate of the calculated distance are provided. The size is equal to or slightly larger than the size of the irradiation spot created by the laser beam pulse emitted from the light emitting unit on the object. The light-transmitting lens of the light-emitting unit and the light-receiving lens of the light-receiving unit are set to different values,
Installed in parallel to each optical axis, in front of and behind each optical axis direction, and with the distance between the optical axes kept equal to or slightly different from half the sum of the diameters. An approach speedometer characterized by. 3. The avalanche photodiode of the light receiving portion is installed so as to be able to finely adjust the arrangement in the directions of two orthogonal axes orthogonal to the optical axis of the light receiving lens. The distance meter described in item 2. 4. The laser diode of the light emitting section is installed so that the laser diode of the light emitting section can be finely adjusted in the direction of two orthogonal axes orthogonal to the optical axis of the laser diode. The range finder described in paragraph.